Air France Mystery: Was Lightning to Blame?

An Air France Airbus A330, carrying 228 people from Rio de Janeiro, Brazil, to Paris, entered an area of strong turbulence and disappeared. The CEO of AirFrance confirms that the airplane most likely crashed into the Atlantic Ocean. Some, including company officials, have speculated that the plane was struck down by lightning, a claim that is not at all outrageous. According to experts, most commercial aircraft are struck by lightning at some point in their lives. But can lightning down a plane? We spoke to the experts about the likelihood of lightning being the culprit in this tragic downing.

Aviation experts agree that it is highly unlikely that lightning alone caused the crash of Air France Flight 447 earlier today. The 2005 Airbus A330-200 twinjet with 228 aboard disappeared on a flight from Rio to Paris shortly after the aircraft sent out automated signals indicated it had suffered a catastrophic electrical failure and a sudden loss of cabin pressure while flying through an area of severe thunderstorms. Late this afternoon the Brazilian Air Force was reporting that the aircraft likely crashed in an area approximately 60 miles south of the Cape Verde Islands off the coast of Senegal. Air France spokesman Francois Brousse this morning stoked mounting speculation when he said "it is possible" the plane was hit by lightning.

Virtually every commercial aircraft in the world is hit by lightning at least once a year according to Dr. Steven Skinner, an aerospace engineering professor at Wichita State University. However, lightning generally passes harmlessly through aluminum-skinned aircraft. And, before they are even installed, the electrical and communication systems aboard are designed, tested and certified to withstand the sudden current surges that a lightning strike produces. These systems are redundant and can be powered by backup generators, including wind-powered ram-air turbines, that deploy in the event all engines fail. Composite aircraft, such as the Boeing 787, have structures impregnated with metallic mesh that perform similarly to all-aluminum aircraft when struck by lightning, giving the energy a clear pathway out of the airplane without damage to structures or systems.

"I don't recall ever hearing about complete electrical failures caused by lightning," says Mike Dargi, vice president of Lightning Technologies Inc. (LTI), a Pittsfield, Mass.Ãbased company that tests aircraft components against the effects of lightning. LTI examines items such as control-surface hinges, radomes, sensors and a gamut of other aircraft electrical components. Dargi says that these components-- and the circuits that connect them--are protected by various structural and electronic safeguards such as bond straps and transorbers, similar to those you find in a personal computer. Dargi says that even the most high-tech aircraft systems, such as fly-by-wire, which control an aircraft through a network of computer-driven electrical actuators over fiber optics, are designed with dual channel backups that automatically switch over in the event of a failure.

LTI's chief engineer, Andy Plumer, has been studying the impact of lightning strikes on aircraft since 1966. He says that standards, first adopted in the 1960s, have mitigated lightning's impact on modern commercial aircraft. The switch to less volatile Jet-A fuel and the fact that modern aircraft are designed to conduct strikes of up to 200,000 amps, Plumer says, are two big factors in improving lightning-strike safety over the last four decades.

The National Transportation Safety Board (NTSB) database confirms that there were 40 lightning-related accidents in the U.S. between 1963 and 1989. However, lightning largely was a contributing--and not a primary--cause of those accidents. The most recent lightning-related accident of a U.S. airliner occurred on November, 29, 2000, when a dormant tailcone antenna of an American Airlines MD-82 was stuck on takeoff from Washington-Dulles Airport. The strike traveled from the antenna up a pair of improperly grounded cables and triggered a cabin fire in the overhead panels. The fire quickly was extinguished and the airplane landed safely.

Plumer notes that lightning is initially blamed for many weather-related crashes, but upon investigation it is "rarely the case."

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